1. Field of the Invention
The present invention relates to a keyboard.
2. Description of the Related Art
A keyboard is used to enter information into a POS (Point of Sales) system of a store etc. The keyboard is provided with a plurality of keyswitch devices which are formed for predetermined information. By pushing a keyswitch device, predetermined information is input. For example, at the surfaces of the keytops, letters, symbols, and other information to be input are engraved. By pushing a keytop, a key input signal corresponding to the input information which is engraved on the keytop can be sent to the system.
In this regard, in recent years, there has been known a keyboard which enables layout of the keytops (key array) to be changed. Further, there has been known a keyboard which enables the sizes of the keytops to be changed. Such keyboards enable the arrangement of the keyboard and size of the keytops to be changed in accordance with the desire of the user, so the convenience of operation is improved.
Japanese Registered Utility Model No. 3023495 discloses a keyboard which enables the keycaps which are used for cash registers to be freely changed. In this keyboard, keybases to which keycaps are to be attached are arranged on a panel at equal intervals. It discloses that by providing connecting columns at predetermined intervals at the back surfaces of the keycaps, replacement is possible without being limited to single dimension keys, double dimension keys, quadruple dimension keys, and other specifications.
Japanese Patent Publication No. 2006-179361A discloses a keyboard which has keytop bases to which keytops which operate contacts of a circuit board by a pushing operation are attached to be able to move in the vertical direction inside a top case and which has keycaps which are attached detachably at the top parts of the keytop bases and stick out upward from the key openings of the top case. In this keyboard, a decorative panel which is attached detachably to the top surface of the top case is provided with keycap insertion holes into which the keycaps are inserted. This discloses that it is possible to replace the keycaps of the keytops simply without disassembling the device case.
As disclosed in Japanese Registered Utility Model No. 3023495, in a keyboard where the size of a keytop which the user pushes can be changed, for example, single dimension keytops can be changed to double dimension keytop etc. In this regard, when changing only a keytop, that is, when changing only the parts which the user pushes, sometimes the operating load when pushing the keytop changes. For example, when single dimension keytops are biased by single coil springs to stick out upward, if attaching a double dimension keytop, it will be biased by two coil springs. For this reason, the operating load of a double dimension keytop becomes larger than the operating load of a single dimension keytop. For example, a double dimension keytop would have to be pushed by about double the force. For this reason, when replacing a keytop, the feeling of operation by the user would deteriorate or the keytop would not be sufficiently pushed and the contact would not be connected.
Furthermore, a keyboard is formed with single contacts able to be operated by single dimension keytops, so if changing single dimension keytops to a double dimension keytop, a plurality of contacts would be connected and mistaken operation would be liable to occur.
For this reason, if changing the size of a keytop, for example, it is possible to detach a member pushing against the membrane sheet. After that, a different sized keytop may be attached. In this regard, a coil spring which pushes against the membrane sheet etc. is arranged inside of a slider which supports the keytop. When changing the size of a keytop, the keytop and slider have to be pulled out, then part of the coil springs etc. has to be detached. There is the problem that a long time is taken for assembling the keyboard or changing the layout of the keytops.